No worries, I wasn’t saying to you directly.
I agree 15 disks is very difficult for a human, probably on a sheer stamina level; but I managed to do 8 in about 15 minutes by playing around (I.e. no practice). They do state that there is a massive drop in performance at this point.
Remember that with Towers of Hanoi every extra disk doubles the number of moves required. So 15 discs is 128x more moves. If you did eight in 15m then fifteen would take you 32 hours.